Telephone system.



G. A. BALS.

TELEPHONE SYSTEM.

APPLICATION FILED JUNE 24, 1912.

Patented July 28, 1914.

slgllllhhhhlnll- CHARLES A. -BALS} OF CHICAGO, ILLINOIS,"ASSiGNeRi BY"MESJNE ASSIGNMENTSf'TO ERANK B. CQOK'COMPANY} OF CHICAGO;

ILLINOISQA GGZR'PORAT 'ION' OF ILLINOIS.

Specification of Letters Patent. 2. Patentd July-28", 1914;.

Application filed June 24, 1812."Seria1-No. 7051412.

To all 'whom' it may concern I I Be it known that 1', CHARLES A, BALs, a

citizen of the United States, residing at Chicago, in the countyj'of Cook and State of lllinois,have' invented a certain new and useful Improvement in Telephone systems, of which the followingis a full, clear, concise, and exact description, reference being had to the accompanying drawings forming a part of this specification.

My invention relates to telephone, systems and in its preferred embodiment includes switching mechanism forming the subject matter of my co-pending application Serial No. 705,413, filed June 24, 1912 but the present invention is not to be limited to the employment of such switching mechanism.

The system of my presentinvention is a so-called intercommunicating system in which the telephone stations are provided with means to enable interc'ommunication there between without the aid of an exchange though in some systems means are provided to also enable telephonic communication betweenany of the stations of the system'and telephone lines which extend to an exchange.

Heretofore mechanism was employed which, among other functions, had the function of locking the telephone station sets in circuit relation with the lines, whicli' have become telephonicallyrelated'to such sets, while the telephone receivers are free of their switch hooks. It is frequently desirable to permit the intercommunicati'ng station party to temporarily hold a line with which his telephonic apparatus has become telephonically connected after such telephonic connection has ceased in order," for example, that conversation may beheld which will not be telephonicall-y transmitted over the line that is thus to'be temporarily held in telephonic disconnection,

My invention has for its object the provision of switching mechanism whereby such electro-magnetically controlled mechanism at an intercommunicatingtelephone station may be operated to sever the telephone connect-ion of a line with such station during the time that the telephone receiver atsuch station is free of its hook; the switching mechanism also including parts "whereby the telephonically disconnected line'may have its line equipment maintained mstatus ua so that the party at'such intercommunicating station resume his telephonic connection with the line that was tempo-' rarily-telephonically disconnected." In the preferred embodiment of the invention a single switch structure i's'ada'pted to'ho'ld sii'ch line and to 'efi'ect the operation "of the -elec- "tro-ina'gnetic mechanism to' efle'ct the desired telephonic disconnection.

1 I 'will'explain'my invention'nior fully 'by reference' t0 5 the accompanying drawing 5 1 showing the*pi'fef'erred form of the '-inven tion "as it isembodied in connection with one type of intercoinmiinicating telephone syste s whose stations are ada t'edfotc'onnection withan'exchange through the intermediation of a trunk line. I will not fully describe the' apparatus illustrated "at each features which are' illustrated' whichdo"not form a part of'my present invention and to which my "present invention is not to be limited. a l I The -apparatus at each" station includes a "telep'honereceiver 1, a telephone'transmitter 2', a telephone switch hook 3 for including the telephone transmitterand' receiver in circuit with and excluding 'from the circuit "of telephonic conductors 4 and 51wl11ch'are extended "into themilltip'le c onneetionswlith the contact springs and 7 oflre'ys 8 (individual to each of the lines extending tothe stations 'where such keys are located "when the key}? is in" the'p'osition indicated at'i'station' B. Each of t'he l' eys 8"'at each-'ofthe station's 'is providedwith' contacts 10 and 11 which are normallyseparated'fromthe contacts 6 and 7 but which are; respect'ively5 'enga'ged [thereby when the key 8 "at station which is calling any of the other stations of the intercommunicati'ng"system or'any station which "is called from an ex ha ge is depressed, it' fbeing "assumed that a" "line i tion 13. Each dog 12- ispivotally' mounted upon a swinging plate 14 which" is engageable by a pin 15 provided upon the lower end of each bar 16. The bar 16 at each station is provided with pins 17 that are worked upon by the keys 8 when the keys are depressed. The equipment at station A is in condition to permit the keys 8 thereat to be depressed. When koy thus free to be depressed is so depressed, the free end of the plate 14 is engaged under the lug carrled by the upper end of the armature 18 as illus-' trated at station B whereby the element 19 is removed from the path of travel of the:

plunger element of the key 9 whereby the" lug 13 is free to ride under the dog 12 so that the nose of said dog will engage the lug, as illustrated at station B, to hold the key in its depressed position as is necessary in the establishment of telephonic connection between the associate telephone set 1, 2 and the line to which the actuated key 8 is individual. As the invention is embodied, the telephone equipment 1, 2 thus locked in telephonic association is mechanically locked without the coincident aid of any electromagnet though I do not limit myselfto this characteristic. The telephonic connection thus mechanically held is adapted to be broken by the associate magnet 20 which, when energized, swings the armature 18 to break the engagement between the armature and the associate plate 14 whereupon the dog 12 carried by such plate is raised out of engagement with the lug 13 to permit the plunger element of the key 9 automatically to be thrust back so as to break the pre viously held telephonic connection. To this end the magnet 20 at one or more of the stations (the equipment now to be described being shown at station A only) is provided with a controlling circuit and'suitably associated switching mechanism, such circuit being traceable from the lower pole of the battery 21, the winding of magnet 20, the now engaged contacts 22, 23, the contacts 24 and 25 of the holding key mechanism to the upperterminal of the battery 21. The contacts 24 and 25 are normally disconnected in order that the magnet 20 may remain inert during the time the associate telephone outfit 1, 2 is mechanically locked in circuit.

The contacts 24 and 25 form part of unitary switching mechanism that includes the contacts 26 and 27 that are normally separated to keep open the bridge conductor across the sides of the trunk line 29, 30 and which bridge conductor includes a magnet 28. When the magnet 28 is energized upon the closure of the contacts 26, 27 (which closure is efl'ected when the closure of contacts 24 and 25 is efiected with the results stated) contacts 31 and 32 are closed for the purpose of maintaining the continuity of the bridge conductor through the winding 28 when the holding key lever 33 is released.

1 battery 21 The armature of the magnet 28 may be pro- 'vided with a visual signal attachment 34 to indicate to the operator whether or not the trunk line is held. The trunk line extends to an exchange (which need not be illustrated) the bridge which is established through the magnet 28 replacing the bridge that'was previously established across the trunk line through the telephonically released equipment 1, 2. The magnet 28 is in high resistance so that when the telephone equipment 1, 2 is again bridged across the trunk line the magnet will be shunted as a consequence of the comparatively low resistance of the bridge conductor including the elements 1 and 2.

The purpose of the holding magnet 28 is to maintain the equipment that is associated with the trunk line at the exchange to which the trunk line extends in status quo whether such trunk line extends to an exchange where it is either manually or automatically extended or not.

A calling party at, say station E, in calling first removes his telephone receiver 1 from the line associated with the electro- 8 individual to the called station, say station A. If station A is idle circuit for the magnet 20 at the calling station is open at the telephone bridge of the called station so that the armature of the magnet 20 of the calling station remains unattracted whereby the switch spring 14, consequent upon the depression of the bar 16 will remain depressed owing to the engagement of this switch spring 14 at 18. The key 9 may now be depressed, owing to the illustrated relationship of its parts 13, 19 to establish circuit for the bell at the called station A, if the called station is idle, which circuit may be traced from the upper pole of the battery 21 the bell 21 at the called station, the switch parts at 23 of the key 9 at the called station, the lower contacts of the switch hook 3 at the called station, the contacts 7, 11 of the depressed key 8 at the calling station, the contacts 22 of thefully depressed key'9 at the calling sta-. tion, thence back to the lower pole of the After the called subscriber at station A responds telephonic circuit is established which is traceable from the transmitter 2 at the calling station, the closed contacts 22 at this station, the contacts 6 and 10 of the depressed key 8, the contact 22 and its complemental contact at the called station, the conductor 5, the transmitter 2 at the called station, the receiver 1 at this station, the upper contacts of the switch hook 3 at this station, the associate conductor 4, the contacts 22 of the key 9 at the called station, the contacts 7, 11- of the key 8 at the calling station, the lower contact 22 and the two contacts beneath it at the calling station, the conductor 4 at this station, the upper pair of switch hook contacts at this station,

telephone practice, the

8 in ividual to the trunk line leading to the exe .iange is depressed and if the line is free fo use the magnet at the calling station is n t energized owing to the absence of battery 13 om the contacts 11. As is well known in telephone bridge at the calling station will operate the line signal'at the-exchange which is connected with the trunk line. It is obvious that the telephonic connection will now include'the con- 5 tacts 6, 7, l0 and the contact below the contact 7 of the depressed key 8 individual to the trunk line, the circuit at the calling stati'on end of the telephone circuit being ap parent from the previous description. It 9 the trunk line is busy it is owing to the depression of the key 8 at some other station, in which event the magnet 20 at the calling station receives current by way of the lower contacts at 11 and the contacts immediately 5 above the same of the key 8 of the calling station and the key 8 at the station which has taken the trunk line for use. When the calling party restores his telephone upon its switch hook circuit for his magnet 20 is closed through the battery 21, this circuit bein traceable from the lower pole of this battery, the winding of the magnet 20 at the calling station, contacts 22 and 23 at the calling station, the lower contacts of the switch hook 3 i at the calling station, the contacts 22 at the calling station, thence back to the upper pole of the battery 21.

It will thus be seen that I have provided a holding switch mechanism which, by one operation, will enable the telephone equipment connected with the trunk line automatically to be disconnected from such line while the line equipment of the trunk line is held in status guo to guard against its disconnection at the exchange to which it extends, a result which is accomplished without the restoration of the receiver 1 upon its switch hook, and while the holding switch happens to be associated with the trunk line, I do not vwish to be limited to this characteristic.

Having thus described my invention, I claim as new and desire to secure by Letters Patent the following 1. An intercommunicating telephone sys tem including telephone lines extending between stations of the system, such stations including telephone receivers and their sup porting switch hooks that take part in governing the telephonic assoclatlon of the stations; electro-magnetically controlled mechanism associated with one of the stations for maintaining the telephonic circuit thereat; switching mechanism supplied in addi tion to the switch hook for altering the cir-- cuit of the electr c-magnetically "controlled mechanism' to effect the telephonic discon nection of the station having such switch hook; and aholdlng switch for preserving the circuit of the telephone line that has become telephonically disconnected from the line associated with the electro-magnetically controlled mechanism.

'2. A telephone system'inclu ding two telev phone lines extending to telephone stations,

oneof said stations having telephonicequipment that includes a telephone receiver and its supporting switch hookthat takes part in governing the telephonic association of its station with its line; electro-magnetically controlled mechanism associated with the line whose station is provided with the cuit thereat; switching mechanism supplied in addition to such switch hook foraltering the circuit of the .electro-magnetically controlled mechanism to eifect the tele phonic disconnection of the station having such switch hook; and a holding switch for preserving the circuit of the telephone line that has become telephonically disconnected from the line associated with theelectromagnetically controlled mechanism. Q I

3. An intercommunicating telephone system including telephone lines extending be tween stations of the system, such stations switch hook for maintaining telephonic cirincluding telephone receivers and their sup-,

porting switch hooks that take part in governing the telephonic association of the stations; electro-magnetically controlled mechmaintaining the telephonic circuitthereat;

to the switch hook for altering the circuit of the electro-magnetically controlled mechanism to effect the telephonic disconnection of the station having such switch hook; a holding switch for preserving the circuit of the telephone line that has become telephonically disconnected from the line associated with the electro-magnetically con-' trolled mechanism; and an electro-magnet made effective by the holding switch to maintain the circuit established by the holding switch, there being circuit connections whereby the telephonic equipment whose line is associated with said electro-magnetically controlled mechanism, when again telephonically connected with the line provided with the holding switch, will effect the operation of said electro-magnct to restore the circuit connections it controls.

4;. A telephone system including two teleanism associated with one of the stations for line whose station is provided with the switch hook for maintaining telephonic circuit thereat; switching mechanism supplied in addition to such switch hook for altering 5 the circuit of the electro-magnetically con-- trolled mechanism to eifect the telephonic :disconnection of the station having such switch hook; a holding switch for preserving the circuit of the telephone line that has become telephonically disconnected from the line associated with the elcctro-magnetically controlled mechanism; and an electro-magnet made efiective by the holding switch to maintain the circuit established by the hold- 15 ing switch, there being circuit connections whereby the telephonic equipment\ whose line is associated with said electro-mz gnetically controlled mechanism, when agai telephonically connected with the line pro ided with the holding switch, will effect th op- 2 eration of said electro-magnet to restore the circuit connections it controls.

In witness whereof, I hereunto subscri e my name this twentieth day of May A.

CHARLES A. BALS.

Witnesses:

E. L. l/VHITE, G. L. CRAGG.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, I). G. 

